Most laser devices typically produce Gaussian or similar beam profiles. However, it is desirable in many laser applications, such as holography, material processing, and lithography, to create a laser beam having a uniform spatial profile to insure uniform illumination of laser energy on the target.
A laser beam having a uniform spatial profile, typically referred to as a flat-top beam, can be obtained by refractive, diffractive, or absorptive elements. Among these methods, the refractive system presents many advantages, including high efficiency, simple structure, and less wavelength dependence, which are essential for high power lasers.
A widely-used refractive laser beam shaper consists of two separate aspherical lenses as shown in FIG. 1. Although this optical system is neither difficult to align or complex, a single lens system, if it exists and does the same job, will be much preferred, especially if it can be mass produced.
What is needed for converting laser beams from Gaussian, or any other spatial distribution, to a flat-top profile is a beam shaper that is simpler to install and simpler to produce and consolidates the beam reshaping function into one single lens.